1. Field of the Invention
The present invention relates to a compressible material suitable for use in a footwear upper. The invention concerns, more particularly, a material formed from thermoplastic sheet with a plurality of compressible projections formed in the sheet.
2 Description of Background Art
Modem athletic footwear is generally fitted to specific individuals based solely upon the overall length of the foot. Foot dimensions, however, vary between individuals in respects that are not accounted for by considering length alone. As a result, many individuals may select improperly-fitted articles of athletic footwear that have the potential to cause discomfort or impair athletic performance.
The fit of an article of footwear is primarily influenced by the shape of the last upon which the footwear is formed. In creating a last, primary importance is given to foot measurements that include the overall length of the foot, width of the foot, height of the first digit, contour of the instep, and at least six girth measurements. In shaping a last for the manufacture of mass-produced footwear, designers utilize foot measurements from a broad spectrum of the population to determine the characteristics of a statistically-average foot. The measurements that comprise the statistically-average foot are then used to shape a last that theoretically achieves a proper fit for a majority of the population. Many individuals, however, do not have a foot with statistically-average proportions and would obtain benefits from footwear that accommodates their unique proportions. For the majority of these individuals, footwear that is offered in a variety of length-width combinations would provide a sufficient fit.
The primary factors that effectively prohibit manufacturers from offering footwear sizes in a variety of length-width combinations relate to manufacturing costs and retail inventory. Each length-width combination for an article of footwear generally requires a unique last that is proportioned for the specific length-width combination. In addition to the cost of generating a relatively large number of lasts, further expenditures are required to alter the manufacturing system each time a different length-width combination is manufactured. Such costs are generally reflected in the final price of the footwear and may make the footwear prohibitively expensive when compared to the cost of similar footwear that is not offered in a variety of widths. With regard to retail inventory, the cost of acquiring footwear in multiple length-width combinations and storing the inventory until sale effectively prohibits at least the smaller retailers from offering various length-width combinations. To ensure availability of specific sizes of footwear, retailers often purchase numerous pairs of footwear for each size. When the typical inventory requirements are further multiplied by numerous widths, the size of the required inventory becomes increasingly large. Accordingly, both manufacturing costs and limitations upon retail inventory effectively prohibit many footwear manufacturers from offering a variety of widths for each size.
In order to accommodate individuals that do not have feet with statistically-average proportions, some prior art footwear designs incorporate fit features that are adjustable. The prior art designs exhibit both automatic and manual mechanisms that permit adjustment of fit factors. An automatic mechanism adjusts by utilizing the pressure of the foot against the interior of the shoe. Usually adjusting for width, the typical automatic mechanism permits a vertical deformation of the upper to translate into a horizontal increase in width. Examples of patents displaying automatic mechanisms include U.S. Pat. No. 5,404,658 to Rosen; 5,325,614 to Rosen; U.S. Pat. No. 5,241,762 to Rosen; U.S. Pat. No. 5,060,402 to Rosen; U.S. Pat. No. 4,967,492 to Rosen; and U.S. Pat. No. 4,858,340 to Pasternak. Manual mechanisms require the wearer to adjust fit through means that include lacing systems, as in U.S. Pat. No. 4,553,342 to Derderian et al. and U.S. Pat. No. 641,642 to Gunn, or screw adjustments, as in U.S. Pat. No. 4,391,048 to Lutz; U.S. Pat. No. 3,686,777 to Rosen; 2,607,133 to Marlowe; and U.S. Pat. No. 5,729,912 to Gutkowski et al.
Although the prior art succeeds in supplying means for adjusting fit factors, many of the prior art designs are not suitable for athletic footwear. Athletic footwear requires an adjustment means that permits fit to be adjusted in specific, localized regions of the footwear. The adjustment mechanisms of the prior art, however, are generally not capable of providing specific, localized fit adjustment.